The present invention relates to an internal combustion engine, and more particularly relates to a spark ignition type internal combustion engine with a particular novel form of combustion chamber and intake port design.
In view of the insistent demands which are made these days upon automotive vehicles in the fields of fuel economy and purity of exhaust gases, there is a constant pressure for the development of internal combustion engines which provide advantages in these areas. Further, maintaining the drivability of the automotive vehicles incorporating such internal combustion engines is also very important. A number of means have been proposed for increasing the fuel efficiency of internal combustion engines while preserving an acceptable standard for the exhaust emissions thereof, and among these means the increasing of the compression ratio of the internal combustion engines figures largely.
However, the increasing of the compression ratio of an internal combustion engine is fraught with a number of problems, chief among which is the danger of detonation or so called "pinking". This detonation or pinking can be reduced and/or avoided by increasing the speed of transmission of flame in the compressed air-fuel mixture in the combustion chamber when the spark plug provides ignition therefor, and accordingly such an increase of the effective or apparent flame transmission speed in the combustion chamber is very helpful from the point of view of design ability to increase the compression ratio of the internal combustion engine, which increases the mechanical octane value of the engine and improves the fuel efficiency thereof. Furthermore, increase of the effective or apparent flame transmission speed in the combustion chamber is effective for stabilizing the combustion of the air-fuel mixture in said combustion chamber between one engine cycle and another, which improves the operation of the internal combustion engine during idling. This is effective for improving the drivability of the vehicle incorporating the internal combustion engine.
It is already known that increasing the amount of turbulence and the amount of microturbulence in the air-fuel mixture in the combustion chamber at the time of combustion thereof is very effective for increasing the effective or apparent flame transmission speed therein. However, it is an old but still a new task to obtain good design for an internal combustion engine, and in particular for a combustion chamber and intake system arangement therefor, which can provide a high degree of such turbulence and microturbulence in the air-fuel mixture in the combustion chambers of the engine, in order to obtain an internal combustion engine having high fuel economy and high purity of exhaust gases.